The NRSA will facilitate my training in the behavioral neurosciences by supporting research on the role of neuroimmune processes in the adaptive response to stressful situations. Specifically, the studies will investigate how individual differences in sympathetic nervous system (SNS) activity contribute to variation in the functioning of the gastrointestinal (gi) system and its vulnerability to infection during stress. Increased SNS activity may lead to disruption of gi homeostasis and subsequent enteric infection by disrupting the protective microflora of the gut, creating a permissive environment for colonization by pathogenic bacteria. These questions will be assessed in infant rhesus monkeys with different behavioral and emotional temperaments, previously shown to be associated with distinct neurochemical profiles. The proposal will test whether gut flora are associated with temperamental attributes, such as emotionally reactive/behaviorally inhibited, in both the baseline and aroused by assessing these monkeys while the mother and subsequent to removal from her at 6 months of age. Finally, I will investigate whether alterations in gi microflora translate into an increased susceptibility to enteric pathogens, such as Shigella, and thus lead to a maladative response to psychological stress. Beyond the specific goals of the project,, this NRSA will allow me to further my graduate training in psychobiological techniques leading to a Ph.D. in Behavioral Neuroscience through the Department of Psychology at the University of Wisconsin.